Quarterly report pursuant to Section 13 or 15(d)

Nature of Operations - Additional Information (Detail)

v3.21.2
Nature of Operations - Additional Information (Detail)
3 Months Ended 6 Months Ended
Jun. 26, 2021
USD ($)
Number
Jun. 26, 2021
USD ($)
Jun. 27, 2020
USD ($)
Jun. 26, 2021
USD ($)
Segments
Jun. 27, 2020
USD ($)
Jan. 18, 2021
Dec. 26, 2020
USD ($)
Jan. 02, 2020
Schedule of Equity Method Investments [Line Items]                
Business Combination Percentage of Net Assets Acquired           100.00%    
Number of reportable segments 2     2        
Assets $ 930,677,988 $ 930,677,988   $ 930,677,988     $ 873,478,745  
Revenue   174,182,389 $ 122,229,623 327,006,657 $ 260,043,418      
Foreign Locations [Member]                
Schedule of Equity Method Investments [Line Items]                
Assets $ 56,116,000 56,116,000   56,116,000     $ 53,424,000  
Revenue   $ 18,345,000 $ 7,255,000 $ 30,905,000 $ 19,544,000      
Janus International Europe Holdings Ltd UK JIE [Member]                
Schedule of Equity Method Investments [Line Items]                
Equity Method Investment, Ownership Percentage 100.00% 100.00%   100.00%        
Janus International Europe Holdings Ltd UK JIE [Member] | Active Supply Design CDM Ltd UKASD [Member]                
Schedule of Equity Method Investments [Line Items]                
Equity Method Investment, Ownership Percentage 100.00% 100.00%   100.00%        
Janus International Europe Holdings Ltd UK JIE [Member] | Steel Storage Australia Asia Steel Storage [Member]                
Schedule of Equity Method Investments [Line Items]                
Equity Method Investment, Ownership Percentage 100.00% 100.00%   100.00%        
Percentage Of Outstanding Shares Purchased               100.00%
Janus Cob bHoldings LLC Cobb [Member] | Asta Industries Inc ASTA [Member]                
Schedule of Equity Method Investments [Line Items]                
Equity Method Investment, Ownership Percentage 100.00% 100.00%   100.00%        
Janus Cob bHoldings LLC Cobb [Member] | Nok Inc NOKE [Member]                
Schedule of Equity Method Investments [Line Items]                
Equity Method Investment, Ownership Percentage 100.00% 100.00%   100.00%        
Janus Cob bHoldings LLC Cobb [Member] | Betco Inc BETCO [Member]                
Schedule of Equity Method Investments [Line Items]                
Equity Method Investment, Ownership Percentage 100.00% 100.00%   100.00%